JPH1170666A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stable printing even when the ink consumption changes drastically without changing the design of the recording head by imparting a compliance capable of absorbing the pressure change of the buffer tank to a connection channel of a recording head and a buffer tank. SOLUTION: An ink inflow opening 22 of a buffer tank 8 is connected with an ink supply tube 10, and an ink outflow opening 23 is connected with an ink supply tube 12 elongating from a recording head 6 via an elastic tube 26 comprising a flexible material to be expanded or contracted by the ink pressure. By providing the elastic tube 26 with a length longer than the length necessary for connecting the ink outflow opening 23 and the ink supply tube 12, or with an easily elastically deformable material such as a silicone rubber, or the like, the compliance can be achieved. As a result, for example, when characters are switched to graphic data so that a large amount of an ink flows from the buffer tank 8 into the recording head 6 instantly, the water hammer action of the elastic tube 26 is absorbed by the compliance and thus it does not cause the continuous oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head and a buffer tank mounted on a carriage which moves in the width direction of a recording sheet, and an ink cartridge housed in a box is provided with an ink supply tube through the buffer tank. The present invention relates to an ink jet recording apparatus that supplies ink to a recording head.

[0002]

2. Description of the Related Art In order to improve print quality in color printing, an ink jet recording apparatus using at least six colors of ink of dark magenta, light magenta, dark cyan, light cyan, yellow, and black has been proposed. .

[0003] In the case of using a multi-color ink as described above, since an ink cartridge for at least six colors is required, the total weight of the carriage becomes large in a recording apparatus in which an ink tank is mounted on the carriage. Therefore, not only is a large output required for the carriage drive motor, but also there are problems such as a large recoil of the carriage upon carriage return.

In order to solve such a problem, as shown in FIG. 6, a buffer tank A as a pressure damper made of a flexible bag is mounted on a carriage, while an ink cartridge B mounted on a box is mounted on the carriage. The buffer tank A is connected to the buffer tank A by the ink supply tube C,
A separate ink supply method for supplying ink to the recording head D via the printer has been proposed.

[0005]

According to this, not only can the ink be reliably supplied to the recording head D, but also the overall weight of the carriage can be reduced to achieve high-speed printing and an extended period of ink replenishment. However, since the buffer tank A and the recording head D are connected by a relatively thin tube E, for example, the print data is switched from a character to a graphic, and the ink in the recording head D is changed. When the amount of consumption changes suddenly, the capacitance component of the recording head D and the flow path resistance of the tube E cause
A water hammer phenomenon occurs due to the inertia of the ink, and the periodic pressure fluctuation acts on the recording head for a short period of time, and the ink amount of the ink droplet changes periodically, as shown in FIG. As can be seen, there is a problem that a dark portion B1 and a light portion B2 are generated, and the print quality is reduced. Of course, in order to solve such a problem, the buffer tank A and the recording head D
It is possible to solve this problem by lowering the flow path resistance of the connection flow path, but there is a problem that a change in the ink supply system of the recording head main body is required and a significant design change is caused. The present invention has been made in view of such a problem, and an object thereof is to cope with a sudden change in ink consumption of a print head without requiring a design change of the print head. An object of the present invention is to provide an ink jet recording apparatus capable of performing stable printing.

[0006]

In order to solve such a problem, according to the present invention, ink of an ink cartridge is supplied to a buffer tank, a part of which is sealed with an elastic film, via an ink supply tube. In an ink jet recording apparatus that performs printing by supplying ink from the buffer tank to a recording head, a connection path between the recording head and the buffer tank is provided with a compliance capable of absorbing a pressure fluctuation of the buffer tank. I made it.

[0007]

In the case where the amount of ink flowing into the print head suddenly changes due to a sudden change in print density and a water hammer occurs in the flow path connecting the buffer tank and the print head, the connection flow between the buffer tank and the print head can be reduced. The pressure fluctuation is absorbed by the path compliance to prevent the propagation to the recording head.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a first embodiment of the present invention. FIG. 1 shows an embodiment of the ink jet recording apparatus of the present invention,
The carriage 1 is connected to a motor 3 by a timing belt 2 and is configured to be guided by a guide member 4 and move parallel to a platen 5. A recording head 6 is provided on a surface corresponding to the platen via a head holder 7. And a buffer tank 8 is mounted on the upper surface.

An ink cartridge 9 is provided on one side of the frame.
And a capping device 11 that is connected to the buffer tank 8 by the ink supply tube 10 and seals the nozzle plate of the recording head 6 in a non-printing area of the moving path of the recording head 6.

FIG. 2 shows an embodiment of the buffer tank 8, in which an ink inlet 22 is formed on one side of a base 21 in which a recess 20 is formed, and an ink outlet 23 is formed on the other side. The opening is sealed with a film 24 having a high air-shielding property, which is deformed by the pressure of the ink. Reference numeral 25 in the drawing denotes a filter provided near the ink outlet.

The buffer tank 8 configured as described above
As shown in FIG. 3, the ink inlet 22 is connected to the ink supply tube 10, and the ink outlet 23 is expanded and contracted by the pressure of the ink. 26 is connected to the ink supply pipe 12 extending from the recording head 6.

The elastic tube 26 is connected to the ink outlet 23 of the buffer tank 8 and the ink supply pipe 1 of the recording head 6.
2 is made longer than necessary to connect them, and is made of silicon rubber or the like which can be easily elastically deformed, and is constructed so as to exhibit compliance of at least 10 minus 13 (m4s2 / kg) or more. I have.

By the way, the elastic tube forming the ink flow path is deteriorated by alkali ions or the like constituting the ink, or changes in the ink composition by permeating the solvent constituting the ink or the atmosphere of the environment. This may cause turbulence, generate air bubbles in the ink, and promote the growth of air bubbles.

In order to avoid such a problem, the elastic tube 26 has an inner layer made of an elastic material having chemical resistance such as a silicone resin or a fluorine resin, and has a high shielding such as a vinyl chloride or a metal film. It is desirable that the outer layer is made of a material having a temper and has at least a two-layer structure.

In this embodiment, when a print signal is supplied to the recording head 6 and printing is performed, ink droplets are ejected from the recording head 6 and at the same time, the ink in the buffer tank 8 is discharged via the elastic tube 26 to the recording head 6. Flow into
The ink 9 of the cartridge 9 flows into the buffer tank 8 via the ink supply tube 10.

By the way, when data is switched from data with a relatively small amount of ink consumption, such as characters, to data that consumes a large amount of ink, such as graphic data,
Since a large amount of ink instantaneously flows from the buffer tank 8 to the recording head 6, the elastic tube 26 connected between the ink outlet 23 of the buffer tank 8 and the ink supply pipe 12 of the recording head 6 performs a water hammer action. Occurs, but is absorbed by the compliance of the elastic tube 26,
The recording head 6 discharges ink droplets having a constant ink amount without reaching the continuous vibration.

When ink corresponding to a large amount of ink consumption flows into the buffer tank 8 via the ink supply tube 10, the inertia of the ink flowing through the ink supply tube 10 changes suddenly, and pressure fluctuations are induced in the buffer tank 8. However, since the ink amount is absorbed by the compliance of the buffer tank 8, the ink amount of the ink droplet does not change.

FIGS. 7A and 7B are print samples in which a solid image portion and a blank portion are repeatedly printed six times at a cycle of 9 milliseconds, and thereafter printing at an intermediate density is performed. In the case of (a) according to the present invention, the density change portion is hardly seen, but in the conventional case of FIG. (B), the dark portion B1 and the light portion B2 are repeatedly generated several times at a constant cycle.

From this, it can be seen that the connection between the recording head 6 and the buffer tank 8 by the elastic tube 26 can be performed regardless of a sudden increase or decrease in the ink consumption of the recording head 6 due to a change in print data or the like. It can be confirmed that this is an effective means for securing a certain printing quality.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the space between the ink outlet 23 of the buffer tank 8 and the ink supply pipe 12 of the recording head 6 is set at both ends. A groove 34 communicating with the connecting portions 30 and 31 is formed in a member 33 having the connecting portions 30 and 31.
4 is a connector 3 sealed with a film 35 having a high air-shielding property.
6 are connected.

According to this embodiment, since compliance can be imparted by the film 35, a greater compliance can be easily imparted as compared with the size of the tube 26 or the like.

The film that separates the ink from the atmosphere degrades due to the alkali ions and the like that make up the ink, and changes the ink composition by permeating the solvent and the atmosphere that make up the ink. This may cause turbulence, generate air bubbles in the ink, and promote the growth of air bubbles.

In order to avoid such a problem, the film 35 is made of an elastic material having chemical resistance such as a silicone resin or a fluorine resin as a contact layer with the ink. It is desirable to form a material having a high air-shielding property as an at least two-layer structure as an air contact layer.

[0024]

As described above, in the present invention, a part of the ink in the ink cartridge is supplied to the buffer tank sealed with the elastic film from the buffer tank to the recording head via the ink supply tube. In an ink-jet recording apparatus that performs printing by supplying ink, the connection path between the recording head and the recording head is provided with a compliance that can absorb the pressure fluctuation of the buffer tank. The pressure fluctuation caused by the water hammer phenomenon occurring in the path can be absorbed by the compliance of the connection flow path, and the printing can be stably performed without changing the ink amount of the ink droplet.

Further, even in the existing apparatus, it is only necessary to replace the components forming the connection flow path between the buffer tank and the recording head. Can be easily improved.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of an ink jet recording apparatus of the present invention.

FIG. 2 is a sectional view showing one embodiment of a buffer tank used in the recording apparatus.

FIG. 3 is a diagram showing one embodiment of a connection structure between a recording head and a buffer tank.

FIG. 4 is a diagram showing another embodiment of the connection structure between the recording head and the buffer tank.

FIG. 5 is a cross-sectional view showing one embodiment of a connection tool.

FIG. 6 is a diagram illustrating an ink supply path of an ink jet recording apparatus including a buffer tank.

FIGS. 7A and 7B are diagrams showing a density change after a solid image and a blank portion are periodically printed in the present invention and a conventional ink jet recording apparatus, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carriage 6 Recording head 7 Head holder 8 Buffer tank 9 Ink cartridge 10 Ink supply tube 12 Ink supply tube

Claims (5)

[Claims] 1. An ink jet type ink supply system for supplying ink from an ink cartridge to a buffer tank partially sealed with an elastic film via an ink supply tube, and supplying ink from the buffer tank to a recording head to perform printing. In the recording apparatus, in a connection flow path between the recording head and the buffer tank,
An ink jet recording apparatus provided with a compliance capable of absorbing the pressure fluctuation of the buffer tank. 2. The ink jet recording apparatus according to claim 1, wherein the connection flow path is constituted by an elastic tube exhibiting compliance capable of absorbing a pressure fluctuation of the buffer tank. 3. The ink jet recording apparatus according to claim 2, wherein the elastic tube is constituted by an inner layer having chemical resistance and an outer layer having air shielding properties. 4. The ink jet recording apparatus according to claim 1, wherein the connection flow path is constituted by a connection tool partly sealed with a film. 5. The ink jet recording apparatus according to claim 4, wherein the film is composed of an ink contact layer having chemical resistance and an air contact layer having air shielding properties.